streams of electrons are to move toward each other the wires must go
along with them.

If the wires are held firmly the electron streams cannot approach one
another for they must stay in the wires. Wires, therefore, perform the
important service of acting as paths for electrons which are traveling
as electric currents. There are other ways in which electrons can be
kept in a path, and other means beside batteries for keeping them going.
It doesn't make any difference so far as the attraction or the repulsion
is concerned why they are following a certain path or why they stay in
it. So far as we know two streams of electrons, following parallel
paths, will always, behave just like the two streams of Fig. 101.

[Illustration: Fig 104]

Suppose, for example, there were two atoms which were each formed by a
nucleus and a number of electrons swinging around about the nucleus as
pictured in Fig. 104. The electrons are going of their own accord and
the nucleus keeps them from flying off at a tangent, the way mud flies
from the wheel of an automobile. Suppose these two atoms are free to
turn but not to move far from their present positions. They will turn so
as to make their electron paths parallel just as did the loops of Fig.
102.

[Illustration: Fig 105]

Now, I don't say that there are any atoms at all like the ones I have
pictured. There is still a great deal to be learned about how electrons
act inside different kinds of atoms. We do know, however, that the atoms
of iron act just as if they were tiny loops with electron streams.

[Illustration: Fig 106]

Suppose we had several loops and that they were lined up like the three
loops in Fig. 105. You can see that they would all attract the other
loop, on the right in the figure. On the other hand if they were grouped
in the triangle of Fig. 106 they would barely affect the loop because
they would be pulling at cross purposes. If a lot of the tiny loops of
the iron atoms are lined up so as to act together and attract other
loops, as in the first figure, we say the iron is magnetized and is a
magnet. In an ordinary piece of iron, however, the atoms are so grouped
that they don't pull together but like the loops of our second figure
pull in different directions and neutralize each other's efforts so that
there is no net effect.

[Illustration: Pl. IX.--Western Electric Loud Speaking Receiver.
Crystal Detector Set of the General Electric Co. Audibility Meter of
Gener